Well, technically we do have that decision. It's just there are consequences. Death, for the obvious. Terrible pain towards loved ones. Loss of a purposeful life. Probably a lot more than I'm listing. Being put IP for these thoughts are to prevent suicide thereby preventing those consequences.

I agree with you, especially on people with little to no hope of recovery (terminally ill, people with dementia, lifelong chronic severe mental illness etc.).

It's like we have the decision to murder, just it's illegal and there are consequences. We have the ability to do whatever we naturally are able to. But it's all about consequences.